Ball and socket joints are used in a variety of applications, including rack and pinion inner tie rod socket assemblies, steering knuckles, drag links, and connecting rod assemblies. Ball and socket joints typically include a generally cylindrical socket member adapted to receive one or more bearings together with a head of a ball stud. The bearing reduces the degree of friction between the socket and ball stud head and is sometimes used to compensate for wear between the stud and socket member by way of a compression preload.
Ball and socket joints have known disadvantages. In particular, the internal surface of the socket must be machined to precise tolerances to ensure a proper bearing fit that is capable of accommodating joint loading and motion requirements. Further, close tolerances are necessary to provide satisfactory wear-life parameters, such as low axial and radial end play under long term load.
To overcome these disadvantages, some ball and socket joints have been provided with bearings having deformable elevations or projections disposed about an outer surface of the bearing to compensate for production tolerances of the joint parts. One known bearing includes elevations in the form of ribs and bars on an outer circumferential surface of bearing, arranged alternating with each other and separated by axially extending grooves. The bars have a greater circumferential width than that of the ribs while the ribs have a greater radial extent that that of the bars. When the bearing is assembled within the socket, the bars bear against the socket only if significant short term loads are acting on the joint. However, known bearings of this type are disadvantageous because the alternating sizes of the elevations produce locally dense high spots on the inside surface of the bearing due to the varying concentrated areas of deformation.
Another known bearing for a ball and socket joint utilizes a plurality of dot or band shaped protrusions which extend circumferentially about an outer surface of a bearing. However, the rings of protrusions are spaced along a central axis. The localized protrusions provide local deformation. There are neither intended nor useable for full surface deformation coverage in a full cavity of the socket. Further, the protrusions require high assembly preloading to deform the protrusions. The high preload in combination with the design of the protrusions creates inner surface problems such as locally dense high spots, thereby causing a likelihood of increased torque variations and more rapid wear of an inner seat surface for the stud.
Therefore, there exists a need for a bearing that can eliminate precise internal machining requirements of the socket in a ball and socket joint, but still produce satisfactory joint integrity without compromising joint performance.